This application claims the benefit of priority from Japanese Patent Application No. 2002-81002 filed on Mar. 22, 2002, herein incorporated by reference in its entirety.
1. Field of the Invention
The present invention relates to a photoresist residue remover composition and, in particular, it relates to a photoresist residue remover composition for removing a photoresist residue after dry etching an interlayer insulating film material, a wiring material, a capacitor, or an electrode material in the production of a semiconductor circuit device.
2. Description of the Related Art
Dry etching is the most important technique used for pattern formation of an interlayer insulating film material, a wiring material, etc. in a production process for a semiconductor circuit device.
Dry etching is a technique that involves forming a pattern by applying a photoresist to a substrate on which a film of an interlayer insulating film material, a wiring material, etc. has been formed by sputtering, CVD, electroplating, spin coating, etc., exposing the photoresist to light and developing it, and then forming an interlayer insulating film pattern or a wiring pattern by dry etching with a reactive gas using the photoresist as a mask. The dry etched substrate is subjected to an ashing treatment in which the photoresist used as the mask is incinerated and removed, and after that a partially remaining photoresist residue, etc. is usually removed with a photoresist stripper.
The photoresist residue referred to here means all of an incompletely incinerated photoresist residue remaining after ashing on the surface of a substrate; a sidewall polymer (also called a sidewall protecting film or rabbit ears) remaining on the sidewall of wiring or a via hole; and an organometallic polymer and a metal oxide remaining on the sidewall and the base of the via hole. The photoresist residue remaining after the dry etching cannot be completely removed by a conventional photoresist stripper containing a combination of an organic solvent and an alkanolamine (for example, JP, A, 5-281753, U.S. Pat. No. 5,480,585). It is conceivable that this is because a part of the photoresist residue after ashing is mineralized together with an etched material such as a wiring material. Therefore, photoresist residue removers containing a fluoride compound (JP, A, 7-201794, EP, A, 662705), a hydroxylamine (U.S. Pat. No. 5,334,332), etc. have been proposed as techniques for removing the photoresist residue remaining after dry etching.
However, these photoresist residue removers require rinsing with an organic solvent such as isopropyl alcohol in order to prevent corrosion of the wiring material and also require a treatment at high temperature in order to completely remove the photoresist residue. Furthermore, since the photoresist residue has a similar composition to that of the wiring material, when treating substrates with these photoresist residue removers there is the problem of corrosion of the wiring material. Because of this, a remover containing a sugar alcohol such as sorbitol as a corrosion inhibitor for the wiring material, etc. (JP, A, 8-262746; U.S. Pat. No. 5,567,574) has been proposed. However, these photoresist residue removers contain an organic compound at a proportion of 50% or more, thus imposing a large burden on the environment, which is undesirable.
Moreover, accompanying the finer structure and higher performance of semiconductor circuit devices in recent years, new wiring materials and new interlayer insulating film materials are being used, and the use, without modification, of conventional photoresist residue removers is approaching its limit.
For example, in order to reduce the wiring resistance so as to fulfill the requirements for finer structure and higher speed of semiconductor circuit devices, copper wiring has been investigated, and it has become possible to form copper wiring by a damascene process. The damascene process is a process in which a wiring pattern is formed as trenches on an interlayer insulating film, copper is embedded by sputtering or electroplating, and unwanted blanket copper is removed using chemical-mechanical polishing (CMP), etc. to form a wiring pattern.
With regard to a resist stripper for this new copper wiring material, there are resist strippers containing a triazole compound, etc. as a corrosion inhibitor for copper (JP, A, 2001-22095, JP, A, 2001-22096, JP, A, 2000-162788), but these resist strippers require a high temperature treatment and rinsing with isopropyl alcohol, etc. as in the above-mentioned photoresist residue removers, and there is the further problem that they contain an organic solvent. Moreover, there is a resist stripper composition containing a benzotriazole derivative as a corrosion inhibitor for copper (JP, A, 2001-83712), and this also contains a water-soluble organic solvent and has the above-mentioned problems. Furthermore, problems of the triazole compound and the benzotriazole derivative having poor biodegradability and imposing a large burden on waste treatment can be cited. Moreover, since the triazole compound and the benzotriazole derivative are poorly water-soluble, these corrosion inhibitors remain on the surface of a wafer after rinsing it with water, thus causing the problem of adverse effects on subsequent steps in some cases.
Similarly, in order to reduce the capacitance between wiring so as to fulfill the demands for finer structure and higher speed of semiconductor circuit devices, a low permittivity interlayer insulating film (the so-called low-k film) has been investigated in recent years. In general, low-k films are organic films such as aromatic aryl compounds, siloxane films such as HSQ (Hydrogen Silsesquioxane) and MSQ (Methyl Silsesquioxane), porous silica films, etc. In the case where a semiconductor circuit device is produced using such a wiring material or interlayer insulating film material, dry etching of the interlayer insulating film material or the various types of low-k film is carried out when forming an upper wiring trench or a via hole providing a connection between lower copper wiring and upper wiring, and at this point a photoresist residue is formed that has a different composition from that formed when using the conventional wiring material and interlayer insulating film material.
Furthermore, since copper and the various types of low-k film have poorer chemical resistance than the conventional wiring material and interlayer insulating film material, a conventional aluminum wiring photoresist residue remover cannot be used without modification when removing the photoresist residue remaining after dry etching. For example, an alkanolamine and a quaternary ammonium compound present in the above photoresist residue remover cause corrosion of copper, which has poor corrosion resistance and, furthermore, cause the film thickness of the various types of low-k film to decrease, and the structure, permittivity, mechanical strength, etc. thereof to change.
A neutral or acidic liquid causes less damage to the low-k film than does an alkaline liquid, and it is thought to be a promising photoresist residue removal component. With regard to neutral or acidic photoresist residue removers, one containing ammonium fluoride, a polar organic solvent, water and ascorbic acid has been proposed in JP, A, 2001-005200. However, the main target of this remover is aluminum wiring material, and a low-k film containing silicon such as a siloxane film or a porous silica film might be noticeably etched in some cases. A remover containing an organic acid has also been proposed (JP, A, 11-316464, U.S. Pat. No. 6,231,677 B1). However, removers containing an organic acid might not be able to satisfactorily remove a photoresist residue remaining on a substrate after ashing. Furthermore, those containing an organic acid generate micro corrosion defects of copper in the vicinity of an interface between the copper and a barrier metal such as Ta or TaN, and these defects become apparent as the device structure becomes finer, thus causing the problem that the reliability of the device is affected. These corrosion defects are called side slits (see FIG. 1).
As hereinbefore described, although various types of photoresist residue removers suitable for conventional wiring materials and interlayer insulating film materials have been obtained, the current situation is that a photoresist residue remover composition that can simultaneously satisfy the above-mentioned needs for semiconductor substrates using new materials has not yet been obtained.
It is therefore an object of the present invention to provide a photoresist residue remover composition that has excellent properties for removing a photoresist residue remaining after dry etching in a production process for a semiconductor circuit device and that does not cause any damage to new wiring materials, new interlayer insulating films, etc.
That is, specifically, the object of the present invention is to provide a photoresist residue remover composition that can suppress corrosion of copper or a copper alloy, including side slits, which are micro corrosion defects of copper in the vicinity of an interface between the copper and a barrier metal such as Ta or TaN, that can also prevent the film thickness of various types of low-k film from decreasing and the structure, permittivity, and mechanical strength thereof from changing, and that has excellent photoresist residue removal properties.
As a result of an intensive investigation by the present inventors in order to solve the above-mentioned problems it has been found that combining a fluoride compound, which causes little corrosion of copper, as a photoresist residue removal component with a specific compound as a component that mainly prevents corrosion can not only prevent corrosion of a wiring material and a low-k film but can also surprisingly suppress the occurrence of side slits, and the present invention has thus been accomplished (see FIG. 2).
That is, the present invention relates to a photoresist residue remover composition that includes one type or two or more types of fluoride compound, and one type or two or more types chosen from the group consisting of glyoxylic acid, ascorbic acid, glucose, fructose, lactose, and mannose (but excluding one that includes ammonium fluoride, a polar organic solvent, water, and ascorbic acid).
Furthermore, the present invention relates to the photoresist residue remover composition wherein the fluoride compound is ammonium fluoride.
Moreover, the present invention relates to the photoresist residue remover composition wherein the concentration of glyoxylic acid, ascorbic acid, glucose, fructose, lactose, and mannose used is 0.01 to 5.0 wt % of the entire composition.
Furthermore, the present invention relates to the photoresist residue remover composition wherein it further includes a surfactant.
Moreover, the present invention relates to the photoresist residue remover composition wherein it is used for a substrate having one type or two or more types chosen from the group consisting of copper, a copper alloy, and a low permittivity (low-k) film.
Furthermore, the present invention relates to the photoresist residue remover composition wherein it contains no polar organic solvent.
Moreover, the present invention relates to use of the photoresist residue remover composition for removing a photoresist residue and a sidewall polymer remaining after dry etching and after ashing.
Since the photoresist residue remover composition of the present invention contains a fluoride compound and the above-mentioned specific compound, it has excellent photoresist residue removal properties and does not cause any damage to wiring materials such as copper and aluminum, interlayer insulating films, etc. Furthermore, copper, which is a new material and has poor chemical resistance, is not corroded and, moreover, the interface between the copper and a barrier metal such as Ta or TaN formed when embedding copper by the damascene process is not corroded, that is, the occurrence of side slits can also be suppressed. In the case where the composition is used for a low-k film, it does not cause a decrease in the film thickness and changes in structure, permittivity, mechanical strength, etc.
Furthermore, in the case where no organic solvent is used, the burden on the environment is small.